Effects of dietary supplementation of a commercial prebiotic Previda® on survival, growth, immune responses and gut microbiota of Pacific white shrimp, Litopenaeus vannamei

A 35-day feeding trial was conducted to evaluate growth, bacterial populations of the gastrointestinal tract (GIT) and immune responses of Litopenaeus vannamei fed diets containing the commercial prebiotic Previda((R)). Diets were formulated to contain Previda((R)) at 0, 0.2, 0.5, 1.0 or 1.6gkg(-1) by weight. At the end of the study, differences in weight gain and survival among treatments were not significant (P>0.05), but denaturing gradient gel electrophoresis analysis revealed that the microbial communities in the GIT changed significantly with the inclusion of dietary Previda((R)) at different levels. Previda((R)) was therefore able to selectively modify the microbial communities in the shrimp's GIT. Although individual bacterial species were not identified, enteric populations in shrimp fed the prebiotic at similar levels of inclusion were genetically similar. In addition, shrimp fed Previda((R)) at 1.6gkg(-1) responded significantly (P<0.05) better immunologically with respect to hemocyte phagocytic capacity, haemolymph protein, hyaline cell counts and haemolymph glucose compared with shrimp fed the basal diet. Although shrimp were not exposed to virulent pathogens in this study, the observed upregulation of some of imm-une responses upon prebiotic supplementation indicates that an improved outcome of such challenges may be anticipated in Previda((R))-fed shrimp under commercial conditions.